In recent years, as virtual reality (abbreviated as VR) technology gradually becomes mature, various virtual reality apparatus arise gradually. Due to Android open source property and sound ecological system, many virtual reality apparatuses are developed based on Android system.
A display procedure of current Android application generally includes two portions: application-side drawing and system-side rendering. For example, Android application invokes SurfaceFlinger service to render, to a display screen, Surface which has passed through measurement, layout and drawing. Generally, when an image is drawn, a so-called “dual buffer” technology is employed. Dual buffer means that two buffer areas (SharedBufferStack) are used: one is called FrontBuffer, and the other is called Backbuffer. A display end processes the FrontBuffer, while a Central Processing Unit (CPU) and a Graphics Processing Unit (GPU) process the BackBuffer. Based on a display refresh mechanism, the image is always drawn in the BackBuffer first, then exchanged with the FrontBuffer, and rendered on the display screen.
In a virtual reality system, there is very crucial index, namely, delay from movement to display, for example, namely, a time period required from a moment when the user's head position changes to a moment when the application draws a corresponding image according to the change and finally displays the image on the display screen. To obtain an optimal user experience, the time period must be very short, preferably so short that the user by no means feels it. If the delay is too long, the user will feel the image shaking and feels dizzy, and the user's experience is undesirable. However, since Android system is not designed for a virtual reality apparatus, the current image display of Android causes the image of the virtual reality apparatus to experience a longer delay from rendering to display, and the user's experience is undesirable.
In addition, other objects, desirable features and characteristics will become apparent from the subsequent summary and detailed description, and the appended claims, taken in conjunction with the accompanying drawings and this background.